Make LongVectors tests run as part of standard test passes (microsoft#7873)

Currently, the various test runners (lit, hcttest.cmd) only run
execution tests where the Priority metadata is <2.

Previously, the LongVectors tests didn't set a value for priority, and
this resulted in them never being selected. This change adds the missing
priority metadata - and then fixes up the tests so they don't
immediately fail if the runtime/device doesn't support SM 6.9!

---------

Co-authored-by: Alex Sepkowski <alexsepkowski@gmail.com>

Author: damyanp

tools/clang/unittests/HLSLExec/LongVectors.cpp

@@ -1432,6 +1432,7 @@ class DxilConf_SM69_Vectorized {
   TEST_CLASS_PROPERTY(
       "Kits.Specification",
       "Device.Graphics.D3D12.DXILCore.ShaderModel69.CoreRequirement")
+  TEST_METHOD_PROPERTY(L"Priority", L"0")
   END_TEST_CLASS()
 
   TEST_CLASS_SETUP(classSetup) {
@@ -1501,8 +1502,14 @@ class DxilConf_SM69_Vectorized {
               OverrideInputSize);
       }
 
-      // Only skip unsupported tests for RITP runs.
-      const bool SkipUnsupported = IsRITP;
+      bool FailIfRequirementsNotMet = false;
+#ifdef _HLK_CONF
+      FailIfRequirementsNotMet = true;
+#endif
+      WEX::TestExecution::RuntimeParameters::TryGetValue(
+          L"FailIfRequirementsNotMet", FailIfRequirementsNotMet);
+
+      const bool SkipUnsupported = !FailIfRequirementsNotMet;
       createDevice(&D3DDevice, ExecTestUtils::D3D_SHADER_MODEL_6_9,
                    SkipUnsupported);
     }